Optical network terminal power failure management

ABSTRACT

Optical network terminal (ONT) power failure management. A system for permitting a customer of a telecommunication company, for whom fiber to the premises (FTTP) has been installed, to control operating features associated with operation of a battery backup unit (BBU) which is used, during power failure, for powering the ONT associated with the FTTP installation and the customer&#39;s telephone(s). The controlling of these features includes utilization of signal-controlled switches, which are manually over-rideable by the customer, thereby providing the desired operating feature control.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to usage of a telecommunicationcompany's fiber to the premises (FTTP) installation at customer premisesand, more particularly, relates to the customer's controlling offeatures associated with a battery backup unit (BBU) used for poweringan optical network terminal (ONT) associated with the FTTP installationduring power failures.

2. Description of Prior Art

Fiber optic infrastructure is currently being deployed by certaintelecommunication companies, including the assignee of the presentinvention, and being operatively connected to their respective customerbases. Fiber optic telecommunication infrastructure offers manyadvantages over the old standard copper wire cabling, not the least ofwhich is vastly increased bandwidth. The plain old telephone system(POTS) had operated, and still operates, with copper wiring. POTS is nowbeing made compatible with fiber optic cabling.

However, a POTS telephone system in combination with this new fiberoptic infrastructure involves certain optically-related and/or otherfunctionality not previously needed in the copper wire cabling world.For example, an optical line terminal (OLT) is needed which may belocated in the central office of the relevant telecommunications companyor at some other regional location (but not on customer premises). TheOLT is communicatively coupled via fiber optic cable to the ONT which isnormally located immediately outside of a customer's premises (typicallymounted on an outside wall some four-five feet above ground).

The ONT is powered by a power supply such as, for example, a powersupply similar, or related, to that described in patent application Ser.No. 11/144,566 filed Jun. 3, 2005, claiming benefit of provisionalapplication Ser. No. 60/576,675 filed Jun. 3, 2004, its assignee, andinventor being, in common with those of this instant applicationentitled: “Multi-Component ONT Power Supply” and incorporated byreference herein in its entirety. That power supply is, in turn, poweredby typical electric utility company power which is subject to powerfailure for reasons including, without limitation, natural disasters andterrorist attacks. During a utility company power failure, traditionalPOTS telephone service over copper wiring is ordinarily able to continuebecause of POTS battery back-up infrastructure which is in place attelecommunication company central offices. This battery backup system isdesigned to maintain POTS telephone service for an entire community.But, that otherwise-available emergency POTS telephone service shall notbe available to a telephone customer using a FTTP system, if the ONTcannot communicate with the OLT over the fiber optic cable because theONT lacks power due to that power failure.

To this end, battery backup has also been provided within the FTTPenvironment for the ONT and for customer telephone instruments connectedto that ONT. But, in contrast with the central office location of POTSbattery backup, ONT battery backup is located proximate its associatedONT, generally within, or near, the telephone customer's premises. ThisONT battery backup unit (BBU) can be designed to include certaincustomer-useful features. One example is an alarm which sounds when thebattery voltage level is low. However, an incessant sounding alarm canbe an annoyance and, to compound the annoyance, the alarm is itselfusing battery energy when emitting sound. These features, under certaincircumstances, can therefore be a detriment instead of a benefit to thecustomer. There is, therefore, a need for managing these features in amanner that reduces or eliminates any customer annoyance otherwisegenerated by these features. The present invention provides a solutionto this shortcoming of the prior art.

SUMMARY OF THE INVENTION

Embodiments of the present invention include methodology and apparatusfor managing an optical network terminal under conditions of a generalpower failure. More specifically, the present invention relates tomanaging certain automatic indicators of battery-backup voltage levelfor the optical network terminal in a manner to allow the customer ameasure of control over these indicators.

In a particular embodiment, the present invention relates to aresidential fiber optic communication system powered by electricity froma utility company. The system permits communication via customerpremises equipment (CPE) including a telephone in a normal mode ofoperation. An OLT is located remotely from the customer premises, andcan be located in a central office of the telephone company associatedwith the customer's telephone. An ONT is located at the customerpremises and is in communication over a fiber optic cable with the OLT.A DC power supply is located at the customer premises for purpose ofsupplying electrical power to the customer's ONT and to the customer'stelephone(s) via the ONT. A rechargeable battery backup unit (BBU) islocated at the customer premises and is rechargeable by the powersupply. The BBU is operatively coupled to the ONT and to the customer'stelephone(s) via the ONT for the purpose of supplying substituteelectrical power to the ONT and to the telephone(s) if and when theutility company electric power fails.

A battery output sensor and controller are located at the customerpremises for monitoring output level, such as output voltage, of thebattery being used for backup. The controller includes means forautomatically signaling the ONT to go into a sleep mode to conservepower when the utility company electric power fails and the batteryoutput level is reduced to a first level. The ONT includes meansresponsive to an off hook telephone signal for over-riding operation ofthe automatically signaling means and thereby reverting the sleep modeback to the normal mode of operation to permit the customer to place acall from the telephone over the system. After the call is completed,the system may automatically go back to the sleep mode.

However, during a utility company power failure where the output levelhas been reduced to an emergency level lower than the first level butgreater than zero, the controller automatically signals the ONT topower-down completely. An emergency switch is connected between theoutput of the BBU and the ONT and is operable by the controller todisconnect the output of the BBU from the ONT. But, before thatdisconnection occurs, the ONT notifies the OLT over the fiber opticcable of the power-down signal. That disconnection stops all furtherpower dissipation from the BBU through the ONT. However that emergencyswitch is also manually-operable by the customer to permit power to bere-supplied to the ONT from the BBU to allow the customer to make anemergency telephone call over the fiber optic cable. Typically, thecustomer would make that emergency call and then open the emergencyswitch To continue to conserve BBU energy or power.

In yet an additional feature of the present invention, an audio alarmprovides an audible warning under conditions of a failure of electricalpower from the utility company. Typically, this may occur when the BBUoutput voltage is at a low level approximately equivalent to theemergency mode level, although this level may fall within a range oflevels running from a non-zero level below the emergency level up to thefully charged battery output level. This audible alarm battery voltagelevel is selected by the telecommunications company which is supplyingthis system. But the customer also has a measure of control. An audioalarm switch, operable by the customer, is provided which shuts-off theaudio alarm for a predetermined time selectable by the customer when theBBU output level is at or below this audible alarm battery voltagelevel, and after which time the audio alarm automatically sounds again.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a FTTP communication system showing the locations ofvarious system components consistent with principles of the presentinvention;

FIG. 2 is a schematic block diagram showing signal paths and power pathsbetween various system components including those of FIG. 1 consistentwith principles of the present invention; and

FIG. 3 is a graph of voltage versus time showing the various levelswhere various events may take place consistent with the principles ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, fiber to the premises (FTTP) system 100 isdepicted. A telecommunication company's central office is shown at theleft-hand side of the drawing, housing optical line terminal (OLT) 101.Other equipment such as switches, routers, server computers, back-upbatteries and other functionality (not shown) may be found in a centraloffice.

On the right hand side of the drawing a schematic profile of acustomer's premises is provided with optical network terminal (ONT) 102which may be mounted on the exterior wall of the customer's premises asshown. A typical mounting would put ONT 102 at about four-five feetabove ground. ONT 102 may be a standard fiber optical terminal whichprovides a suitable terminus for fiber optic cable 103. Other systemcomponents included within or at the customer premises include ONT powersupply105, BBU 106 as battery backup for ONT 102, and customer premisesequipment (CPE) 107 which includes any residential-styled communicationequipment such as telephones, facsimile devices, televisions, computersystems, etc. Either power supply 105 or BBU 106 or both may bephysically located within the housing for ONT 102, or may be locatedinside the customer premises. It should be understood that electricalpower is brought to the customer premises by an electrical utilitycompany (not shown).

Signals received by OLT 101 over fiber optic cable 103 from ONT 102 maybe processed in OLT 101 and may be forwarded to other equipment (notshown) located within the central office for further processing beforerouting those signals to their ultimate destination outside of thecentral office. In the opposite direction, signals to be forwarded fromOLT 101 over fiber optic cable 103 to ONT 102 had previously beenreceived by the central office from a source or sources located outsideof the central office, may have been processed by the other equipment(not shown) located within the central office and may be furtherprocessed by OLT 101 before being forwarded from OLT 101 over cable 103.

FIG. 2 is a schematic block diagram showing signal paths and power pathsbetween various system components, including those of FIG. 1. Forclarity purposes, power paths are shown in wide-bus format and thesignal paths are depicted as single line connectives. It should beunderstood that the thickness of the actual power cable and thethicknesses of the actual signal cables are not necessarily related toeach other in the proportions shown in the drawing. Also, the spatialrelationship shown in FIG. 1 may not be strictly maintained in FIG. 2.For example, the telephone company battery backup 219 in FIG. 2 isactually physically located within the telecommunication company'scentral office, and the utility company's electric power, shown withinFIG. 2 as block 200 for clarity of illustration, is actually brought tothe customer's premises in accordance with typical power distributionfrom a utility company.

Power Distribution:

Continuing with FIG. 2, customer premises equipment CPE 107 comprisesCPE107A (exclusively telephone or telephones) and CPE 107B (allnon-telephonic consumer premises equipment such as television, etc.).Starting with the utility company electric power functionality 200, itcan be seen that electric power is distributed to CPE 107B on power bus215 and to ONT power supply 105 on power bus 201. ONT power supply 105,in turn, distributes power to ONT 102 over power bus 206/205 and to BBU106 over power bus 202. BBU 106, in turn, and only if utility companyelectric power 200 has failed, distributes power to ONT 102 throughpower bus 203/204/205 by way of emergency switch 210, and distributespower to audio alarm 220 through power bus 207/208 by way of timerswitch 211.

Power output from ONT 102 is supplied to the customer's telephone(s)107A over power bus 217. This power is derived from ONT power supply 105if there is no power failure, and is derived from ONT BBU 106 if thereis a power failure.

In the upper left of FIG. 2, other power distribution is shown asderiving from the telephone company's central office battery backup 219,and as being distributed over power bus 218 to the central offices OLTunit 101. Therefore, if there is a power failure affecting both thecustomer's premises as well as the telephone company's central office,telephone company battery backup 219 substitute-powers the equipmentlocated within the central office such as OLT 101, but does not supplysubstitute power to ONT 102 or to CPE 107.

Signal Distribution:

Referring to battery level sensor and controller 209, (hereinafter“controller 209”) at the lower left of FIG. 2, it can be seen thatseveral signal paths emanate therefrom. Controller 209 includesfunctionality that senses the voltage level output of BBU 106 via powerbus 203. When there has not been a power failure for some period oftime, the batteries (not shown) of BBU 106 may be fully charged by powersupply 105. When a power failure occurs, whereupon BBU 106 is pressedinto service, output of the batteries of BBU 106 generally declines overtime. This is illustrated in greater detail in FIG. 3.

FIG. 3 is a graph of voltage output from the batteries of BBU 106 as afunction of time. This discharge curve is merely exemplary, and curvedepicted in FIG. 3 can assume virtually any shape having a negative orzero slope. At time zero, the batteries are fully charged, as shown. Attime T1, the batteries have discharged to a point where the dischargecurve intersects, at point “A”, the sleep mode level, also referred toherein as level 1. This level might be, for example, approximately75%-90% of the fully charged level, but could be virtually anypercentage of the fully charged level above an emergency level, definedbelow.

At time T2, the battery voltage has continued to discharge to a pointwhere the discharge curve intersects, at point “B”, with the audio alarmlevel. The alarm level is pre-set at the telecommunications company, andit is normally intended to signal low battery voltage, but it could beused to signal something other than low battery voltage. The settablerange for the audio alarm is from just above zero to just under fullycharged as shown by bracket “C”. If set at just above zero, it shallgive an audio signal just as the batteries fail completely. If set atjust under fully charged, it shall give an audio signal indicative ofthe onset of a power failure. This latter setting may be useful underthe circumstances of a power failure during daytime where no electriclights or appliances are operating and where a customer may nototherwise have been aware of the power failure. Typically, the audioalarm level can be set to be at or near emergency mode level, with whichthe voltage discharge curve intersects at time T3 and at point “D.”

It should be understood that the system can remain in sleep mode frompoint A, the level at which the sleep mode was initiated, down to pointD, even though the audible alarm signifying the power outage may havesounded in the interim. Also, intermittent telephone usage may haveoccurred in the interim, as described below. Finally, if and when thebatteries become fully discharged, at time T4, the battery voltagedischarge curve intersects, at point “E”, with a zero level of voltage.

Returning to FIG. 2, while also referring back to FIG. 3, when thevoltage discharge curve is at point “A”, at the first level (sleep modelevel) of output from BBU 106, a sleep signal is sent over signal line213 from controller 209 to ONT 102 requesting that ONT 102 enter a sleepor standby mode. In the sleep mode, multiple functions of ONT 102 arestopped to conserve power. For example, the video services could be shutdown within 30 seconds, and the data services could be shut down within15 minutes. ONT 102 remains in this sleep mode until one of two thingshappen: (1) electric power 200 is restored or (2) the customer lifts itstelephone 107A off hook, whichever occurs first. The latter event sendsa signal from telephone(s) 107A over signal line 216 to ONT 102 which,in combination with the powering of ONT 102 by battery backup 106,returns ONT 102 to a fully functional unit for purposes of allowing thisparticular telephone call to be made. ONT 102 and telephone 107A areboth powered by BBU 106 having initial voltage output at sleep modelevel. After the customer has completed that telephone call and hangsthe phone back on the hook, the batteries of BBU 106 have furtherdischarged somewhat and ONT 102 reverts to sleep mode if power 200 hasnot yet been restored. But, if power was restored during that telephonecall, ONT 102 remains fully functional and does not revert to sleepmode. Additional calls can be made during power failure in sleep mode,provided that the voltage level output of BBU 106 remains above theemergency voltage level.

If the voltage level output of BBU 106 drops to an emergency voltagelevel, then ONT 102 can be automatically and completely turned off. Theemergency level, shown as intersecting the voltage discharge curve atpoint “D” in FIG. 3, is a level that is pre-determined by thetelecommunications company that supplies ONT unit 102. This emergencylevel provides sufficient residual energy in BBU 106 to allow, e.g., oneor two more telephone calls of limited duration. Under these conditions,controller 209 provides a shut-off signal on signal line 212 to switch210, which causes it to open. The power which had been supplied overpower bus 203/204/205 to ONT 102 through switch 210 is therebyinterrupted, whereby ONT 102 shuts off and cuts off power to telephone107A. However, switch 210 is also manually operable by the customer, andif an emergency phone call must be made, that switch can be manuallyclosed, thereby over-riding the automatic shut-down signal. There shallbe sufficient energy remaining in BBU 106 to power ONT 102 and telephone107A to allow that emergency phone call. Under these conditions, it maytake a little time, perhaps ten minutes, for ONT 102 to return tooperating condition before communication over the telephone actuallytakes place.

Referring next to audio alarm 220, it can sound only during powerfailure. It can be energized by BBU 106 via power buses 207/208 throughswitch 211 only when there is power failure. But switch 211 has to beclosed to allow power to be applied to alarm 220. Switch 211 iscontrolled by a control signal over signal line 214 which is generatedwhen the alarm level is triggered by the discharging battery voltage(Point B in FIG. 3). This level is set by the equipment supplier.However, that audible signal, as useful as it may be to alert thetelephone customer or other members of the customer premises householdof the power failure, can quickly become annoying to hear. Furthermore,the audible sound itself saps electrical energy from BBU 106 therebymaking the batteries deplete more quickly than otherwise. The customerhas capability of avoiding these problems.

Indeed, switch 211 is manually operable and it can be opened by thecustomer at any time which shall interrupt the application of electricalpower via power bus 207/208 thereby cause the alarm to stop sounding ifit had been on. This is an improvement provided to the customer whichpermits him/her to remove what might become an annoying sound not tomention saving precious battery power at the same time.

In addition, switch 211 has a controllable timing feature (not shown)associated with it. Switch 211 can be set by the customer for certainperiods of time, for example one hour. If set to one hour, then ifswitch 211 is manually opened, it shall remain open for one hour. Afterthat hour, it automatically closes allowing BBU power to be reapplied toalarm 220, thereby sounding the audible alarm. Thus, not only can thealarm be temporarily silenced by the customer, but the duration of thesilence between alarm soundings is also under the control of thecustomer.

While illustrative embodiments of the present invention have been shownand described, numerous variations and alternative embodiments may occurto those skilled in the art. For example, as noted, the thresholdsetting of the alarm is predetermined by the equipment provider. Theequipment provider could offer various models with various alarmsettings if that were deemed to be a useful marketing strategy. Othervariations and alternative embodiments are contemplated, and can be madewithout departing from the spirit and scope of the present invention asdefined in the appended claims.

1. A residential fiber optic communication system powered by utilitycompany electric power, said system permitting communication viacustomer premises equipment (CPE) including a telephone in a normal modeof operation, said system comprising: an optical line terminal (OLT)located remotely from said customer premises; an optical networkterminal (ONT) located at said customer premises in communication over afiber optic cable with said (OLT); a DC power supply located at saidcustomer premises for supplying DC electrical power to said ONT; arechargeable battery backup unit (BBU) located at said customer premisesand rechargeable by said power supply, said BBU being operativelycoupled to said ONT to supply substitute DC electrical power to said ONTif and when said utility company electric power fails; a battery outputsensor and controller located at said customer premises for monitoringoutput level of said battery; said controller including means forautomatically signaling said ONT to go into a sleep mode to conservepower when said utility company electric power fails and said outputlevel is reduced to a first level; and said ONT including meansresponsive to an off hook telephone signal for over-riding operation ofsaid automatically signaling means and thereby reverting said sleep modeback to said normal mode of operation to permit said customer to place acall from said telephone over said system.
 2. The system of claim 1wherein said controller further comprises means for causing said systemto go back to said sleep mode after said telephone call is completed. 3.The system of claim 1 wherein said controller further comprises: meansfor automatically signaling said ONT to power-down completely when saidutility company power fails and said output level is reduced to anemergency level, said emergency level being lower than said first levelbut greater than zero.
 4. The system of claim 3 wherein said automaticsignaling means further comprises: an emergency switch connected betweenthe output of said BBU and said ONT and operable by said controller;wherein said ONT first notifies said OLT via said fiber optic cable ofsaid power-down signaling and then powers-down completely by beingdisconnected from said output of said BBU by operation of said emergencyswitch.
 5. The system of claim 4 wherein said emergency switch ismanually-operable by said customer, to permit power to be re-supplied tosaid ONT from said BBU for purposes of allowing said customer to make anemergency telephone call from said telephone via said ONT, said fiberoptic cable and said OLT.
 6. The system of claim 3 further comprising:an audio alarm to provide an audible warning under condition of afailure of electric power from said utility company; and an audio alarmswitch, operable by said customer, to shut-off the audio alarm for apredetermined time selectable by said customer.
 7. The system of claim 6wherein the audio alarm level is approximately equivalent to saidemergency mode level, whereby sounding of the alarm indicates usage, orimpending usage, of emergency battery energy capacity.
 8. The system ofclaim 1 wherein said level is battery voltage level.